Abstract

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Low-carbon steel (LCS) is applied in numerous engineering applications, such as construction, automobile manufacturing, and product and component manufacturing, due to its unique mechanical properties. They are readily available, hence are very cost-effective when considered in any application. However, they are usually affected by corrosion when exposed to chloride-induced media, due to the penetration of chloride ions. Biopolymer coatings electrodeposited on the surface of metals have been shown to restrict the penetration of chloride ions into the metallic substrate, thereby slowing down the corrosion rate. This study was aimed towards electrodepositing Zinc-magnesium oxide-cellulose nano-particle coatings (Zn-xMnO-xCn) on LCS for improved corrosion resistance in sodium chloride media. The gravimetric technique was used to determine the corrosion rates of the deposited coatings (samples). The samples’ morphology and composition were determined via optical microscopy and scanning electron microscopy, equipped with an energy-dispersive spectrometer. Corrosion data from the results showed that all the coatings recorded lower corrosion rate values than that of the LCS substrate, whose value was 5.0025 mm/y. Among the coatings, sample M10 (Zn-20gMgO-20gCn) had the least corrosion rate value of 0.2582 mm/y, corresponding to a coating protection efficiency of 95% on the LCS. The highest corrosion rate value was recorded by M7 (Zn-20gMgO-5gCn) with a value of 2.2236 mm/y corresponding to a protection efficiency of 56% on the LCS. The coating morphologies revealed uniformly distributed and fine grains on the LCS’ surface. The study showed that the Zn-xMnO-xCn coatings were able to form protective barriers on the substrate in the sodium chloride media.

Keywords: Chloride, ions, coatings, substrates, corrosion